WASHINGTON — The Pentagon will buy and operate one or two commercial imagery satellites and plans to design and build another with more sophisticated spying capabilities, according to government and private industry officials.

The satellites could spy on enemy troop movements, spot construction at suspected nuclear sites, and alert commanders to militant training camps.

The Broad Area Space-Based Imagery Collector satellite system, or BASIC, will cost between $2 billion and $4 billion. It would add to the secret constellation of satellites that now circle the Earth, producing still images that are pieced together into one large mosaic.

A single satellite can visit one spot on Earth once or twice every day. BASIC’s additional satellites will allow multiple passes over the same sites, alerting American government users to potential trouble, humanitarian crises, or natural disasters like floods.

The announcement of the BASIC program, expected this week, has been delayed for months, with Pentagon, Air Force, and National Reconnaissance Office officials fighting over who should be in charge of buying, building, and operating the satellites. They have also debated whose needs the system will cater to: senior military commanders or policymakers in Washington.

At stake was not just money but power: Billion-dollar budgets are up for grabs, and the agencies’ traditional missions and ways of doing business have been hanging in the balance.

The National Reconnaissance Office ultimately won the right to buy and operate the satellites, besting the Air Force. And military commanders’ needs trumped the White House. They will, for the first time, have the opportunity to dictate what satellites will photograph when they pass overhead. The concept is known as “assured tasking.”

“The battlefield today is so dynamic the warfighter needs to be able to respond at a moment’s notice. Knowing they have the opportunity to have assured tasking in the next pass of satellite becomes very critical and helpful in the planning of their operations,” the Pentagon director for space and intelligence capability acquisition, Josh Hartman, told the Associated Press.

Military commanders have long desired that kind of tasking control. Now, they submit their requests to a national intelligence authority that prioritizes the missions. And sometimes those requests are delayed or rejected.

The new satellite system is meant to bridge what intelligence agencies fear will become a gap caused by the cancellation in September 2005 of a major component of the Future Imagery Architecture system overseen by the National Reconnaissance Office. Prime contractor the Boeing Co., headquartered in Chicago, ran into technical problems developing the satellite and spent nearly $10 billion, blowing its budget by $3 billion to $5 billion before the Pentagon pulled the plug, according to industry experts and government reports.

The Pentagon hopes BASIC will fill in some of the lost capabilities in key ways:

It will increase the amount of imagery the National Geospatial Intelligence Agency buys from commercial satellite companies GeoEye of Dulles, Va., and DigitalGlobe of Longmont, Colo., which are expected to put four new satellites into orbit by 2013.

The U.S. military now has a $1 billion contract with two commercial satellite companies to buy space imagery. An American commercial satellite launched in September by DigitalGlobe can make out the outline of 20-inch object from space. This year, GeoEye is launching a satellite with the ability to see the outlines of a 16-inch object. By 2011, that capability is expected to sharpen to nearly 10 inches. Secret government imagery satellites are believed by experts to have better than 6-inch resolution.